Mobile devices such as cellular telephones have sound holes in the housing of the device that function as a port to allow acoustic signals to travel from a transducer mounted within the housing to a user's ear. The exact size, shape, location, and number of sound holes are important with respect to the design, marketing, and visual appeal of the mobile device. For example, by arranging the sound holes in a particular pattern the holes may be used as a source identifier such as a trademark or to convey a particular look. However, the sound holes may also detract from the visual appeal of a device due to their size, location, or asymmetry, or they may pose a functionality issue if they are too small and tend to become obstructed by debris. The sound holes in a mobile device are designed so that the acoustic performance of the mobile device does not vary substantially regardless of whether the user is right-handed or left-handed or whether the user is listening with their right ear or left ear.
Presently, two or more sound holes are required in a mobile device containing transducers designed to have low acoustic impedance in order to obtain the desired frequency response necessary to achieve the optimum acoustical performance of the mobile device. The size, shape, location, and number of sound holes in a mobile device are also largely dependent upon the location of the transducer inside the mobile device.